Now that the human genome has been sequenced, there has been a surge in interest in identifying the function of the proteins coded by the newly identified genes. A variety of in vitro biochemical approaches exist for studying protein function, e.g., methods for measuring enzymatic activities, methods for measuring binding interactions, etc. These methods generally require some advance knowledge of the types of activities that might be found, e.g., the structure of an enzymatic substrate or potential binding partner.
An alternative approach is to transfect a cell with a gene of interest and look for the ability of the gene to change a phenotype of the cell. The advantage of this cell-based approach is that it allows identification of proteins that are involved in a specific phenotype or cell behavior without knowing the biological pathways involved in that phenotype or cell behavior. A drawback of cell-based assays is that they tend to be laborious and not amenable to the high-throughput screening of genes. There is a need for improved high-throughput cell-based methods for identifying the function of proteins.